Light sensitive material



' soluble salts are particularly suitable.

especially the benzanthrone sulfonic acids.

Patented May 5, 1942 PATENT OFFICE' LIGHT SENSITIVE MATERIAL Gottlieb von Poser, Wiesbaden, and Maximilian Paul Schmidt, Wiesbaden-Biebrich, Germany No Drawing. Application November 14, 1940, Se-

rial No. 365,652. In Germany Claims.

The present invention relates to light sensitive materials which may be used for photographic purposes.

It is known that the light-sensitiveness of such organic dyestuffs as change their color or bleach out on exposure to light may be enhanced by adding sensitizers to the dyestufl's.-. As such sensitizers there have been proposed, for instance, thiosinamine and anethole. By applying combinations of suitable dyestuffs with such. sensitizers on paperior a similar support, light-sensibasic groups, preferably amino groups.

are also suitable triphenylmethane dyestuffs for tive materials are obtained which may be used for photographic purposes. Such light-sensitive materials, however, have hitherto not attained a great importance in view of the fact that the light-sensitiveness of the dyestuffs which in most cases is only very small is not sufliciently enhanced by the sensitizers so that the light-sensitive materials require too long times of exposure.

Now, we have found that the anthraquinone and the derivatives thereof are suitable sensitizers for the above mentioned light-sensitive layers containing organic dyestuffs. The derivatives which have a good solubility in water and are colorless or only feebly colored may be used with special advantage. Thus, for instance, the benzene nuclei of the anthraquinone may carry simple substituents such as allryl groups, halogen atoms, carboxylic or sulfoiiic acid groups. Anthraquinone sulfonic acids and their water V Above all beta-anthraquinone sulfonic acids, for instance, 2.7-anthraquinone disulfonic acid must be mentioned. 2-anthraquinone monosulfonic acid may also be used with good success. Instead of the anthraquinone or its derivatives there may be used the benzanthrone or the derivatives thereof,

latter compounds, however, are notso effective as the anthraquinone compounds.

By means of the compounds used as sensitizers according to the present invention the light-sensitiveness of dyestuffs may be enhancedto a conthe light-sensitiveness obtained by sensitization of dyestuffs with known sensitizers. It,v is even poss ifle, according to this invention, to sensitize dyestuffs, which per se are practically not sensitive to light, to such an extent that they show a great light-sensitiveness and may, consequently be used'for photographic purposes.

The sensitizers used according to the present invention are preferably applied together with azo-dyestufl's, for instance, very simple azo-dyestufis, such as amino-azobenzene or complicated 5 The Y siderable extent, 1. e. in general to a multipleof November 20,

a'zo-dyestuffs, such as, disazo-dyestufis, .trisazodyestuffs or tetrokisazo-dyestuifs. The best re-' sults are generally obtained with mon'oazo-dyestuffs, especially such as contain one or several There instance, blue or violet triphenylmethane dyestuffs. When combined with the said sensitizers they very quickly turn yellow-green .or green, respectively, on exposure to light. Oxazine dyestuffs such as Nile-blue or quinone dyestuffs such as Alizarinirisol D or Alizarinsaphirol B (see Schultz Farbstofltabellen 1931, Nos. 1,029, 1,196 and 1,187) and other water soluble dyestuffs will also be used. It may easily be ascertained by experiment whether and to which extent a dyestuii is suitable. For this purpose it is only necessary to add one of the sensitizers to a dilute dyestuil' solution, to pour the solution on absorptive paper and to expose the latter half covered for a short time to arc or sun light or to another source of light emitting actinic light.

It is suitable to add to the dyestuffs considerable amounts of vsensitizers. In some cases it' is advantageous that the quantity of the sensitizer surpasses that of the dyestufi'. In general it is advisable to add to the mixturesof dyestuffs and sensitizers an acid since in this manner th dyestuffs may often be brought into aform especially The said combinations of dyestuii's'and sensitizers may be applied in :the form of their solutions on paper or any other support. Particularly good results have been obtained with these combinations in light-sensitizingfoils, for instance, of regenerated cellulose or cellulose esters since on these supports the change of the dyestuffs occurs very rapidly. The light-sensitive layers thus obtained may be used. for various purposes, for instance, for photometric researches since the changes. of the dyestuffs are well visible and may, therefore, easily be observed. The

layers may also be applied in the color photography or in heliographicprinting for the preparation of prints. In the latter case there are advantageously used for the preparation of prints 'which shall be inspected dark, for instance, blue dyestuffs preferably those which entirely bleach out on exposure to light. For the'preparation of so called intermediate originals, however, which serve for the preparation of further prints, yellow dyestufls are generally to be preferred. 7

A very important practical advantage of, the said light-sensitive layers resides in the fact that they 'are of good stability in the dark. As is sensitive to light, asmore fully described below."

known, this is not the case with other light-sensitive layers. Also with such light-sensitive layers which contain thiosinamine besides the dyestuffs it may often be observed that a change of thecolor or a decolorization takes place even when the material is stored in the dark.

In the preparation of prints by means of the new light-sensitive layers the fixation may be carried through in various ways according to the properties of the dyestuffs and sensitizers used. If in the case of a bleaching-out layer the sensitizer is soluble in a solvent in which the dyestuff does not dissolve, the sensitizer may be removed after exposure bywashing out with the respective solvent. In many cases water may be used as solvent. If dyestuffs are used which per se are practically insensitive to light, stable prints may be obtained in this manner. Sometimes it is even possible to use for the fixation a liquid which dissolves the sensitizer and in which the dyestufi per se is likewise soluble. This method may be applied in case the dyestuif has substantive properties relative to the support or is rendered insoluble by a treatment with a mordant or a like operation.

In some cases the dyestuff differs in its form according to the pH-value of the layer. It often occurs that of the two forms which are generally of different color that one existing at a higher pH-value is not or hardly sensitive to light whereas that one existing at a lower pHvalue is sensitive to light. The dyestuif is then used in the latter form, the fixation being performed in the dry way by treating the light-sensitive material with gaseous ammonia. V

t The following examples illustrate the invenion:

( 1) A film of regenerated cellulose is impregnated with a solution containing per liter of water grams of the dyestuff prepared by coupling diazotized sulfonllic acid with beta-naphthol (Orange II Schultz Farbstofitabellen No. 189) grams of phosphoric acid and. 25 grams of 2.7-anthraquinone disulfonate of sodium. By

. exposing the orange-red film thus obtained to the light of an arc lamp, the coloration disappears in a few minutes. The film may, for instance, be used for photometric purposes. Films of similar properties may be obtained with the aid of azo-dyestufis prepared by coupling of the following components: diazotized aniline and dimethylaniline (butteryellow 0, Schultz Farbstofftabellen No. 28) 2.4-dimethoxy-l-diazobenzene and phenol, 4-chloro-l-diazobenzene-Z-sulfonic acid and dibutylaniline, 4-chloro-l-diazobenzene 2- sulfonic acid and diphenylamine, 2.5-dichloro-1- diazobenzene-i-sulfonic acid and N-ethyl-N- benzyl-aniline, 1-diazo-4-(2'5'-dichlorobenzyl) aniline and phenol. There may also be used diamine pure blue, diamine blue BB, half wool black K and benzo-brown B (see Schultz Farbstofitabellen Nos. 510, 5,13, 671 and 689).

(2) 10 grams of the dyestuff prepared by coupling 4-diazo dimethylaniline and phenol,

grams of phosphoric acid and 20 grams of anthraquinone-beta-sulfonate of potassium are simultaneously dissolved in a mixture of 500 cc. of

' water and 500 cc. of alcohol By impregnation withthis solution paper or foils may be made sensitive to light.

(3)' The azo-dyestuff obtained from diazotized 4- ohloraniline and N-ethyl-N-cyclohexylaniline is sulfonated in known manner in order to impart to the dyestuff a good solubility in water. grams of the sulfonated dyestufi', 20 grams of phosphoric acid and grams of 2.7-anthraquinone disulfonate of sodium are together dissolved in 1 liter of water. This solution is applied on one side of a superficially saponified foil consisting of acetyl cellulose. The bluish-red material i is exposed under an original to the light of an arc lamp. At the places struck by the light the dyestufi bleaches out very quickly. The prints may be fixed by treating them with gaseous ammonia whereby the dyestuff assume a lighte yellow color stable to light. The prints obtained are suitable for further printing on diazo-photoprinting material. Instead of 2.7-anthraquinone sulfonate of sodium there may be used grams of 1. i-dichlor0-2-anthraquinone sulfonate of potassium. It is also possible to use instead of the dichloro compound, 1.2-diamino-anthraquinone- 3-sulionic acid in form of its sodium or potassium salt, the amino compounds, however, being in general less suitable on account of an intense coloration of their own.

(4) A cellulose hydrate foil is impregnated with a solution of 5 grams of erioglaucine (see Schultz, Farbstoiftabellen 1931, N0. 770) 10 grams of phosphoric acid and 20 grams of anthraquinone-2.7-disulfonate of sodium 1 liter of water. When exposed to light under an original the exposed parts change from blue to yellow-green. These exposed yellow-green parts absorb chemically active light better than the unexposed blue parts. Such a film may be used for the preparation of an intermediate original in case a positive shall be prepared on diazo-photoprinting paper from a negative. Like the erioglaucine there may be applied in a similar manner other triphenylmethane dyestuffs, for instance Acid Violet iBN,

Victoria-Blue 4R, Night-Blue or Water-Blue R, Naphthalene-Green V or Malachite-Green B. Also the oxazine dyestuff Nile Blue BX is likewise suitable (see Schultz, Farbstofftabellen Nos.

phenylethylene with diazotized sulfanilic acid (see Dissertation of Karl Riener, Bonn, 1938) 15 grams of phosphoric acid and 20 grams of 2.6- anthraquinone-disulfonate of sodium. The film obtained has a good sensibility to light.

(6) The azo-dyestufi obtained by diazotization' of 4-chloraniline-3-sulfonic acid and subsequent coupling with dibenzylaniline is subsequently sulfonated in order to improve its solubility in water.

A light-sensitive material is prepared by impregnating a cellulosehydrate film with a solution containing per liter of water 15 grams of the sulfonated dyestufl, 20 grams of phosphoric acid and 40 grams of the sodium salt of benzanthrone-sulfonic acid: The latter is obtained by introducing benzanthrone into 6 or 8 times the quantity of fuming sulfuric acid containing 20% of free sulfuric anhydride, the temperature of the mixture rising to about 60 C. and sulfonatlon taking place. When a test portion shows that the product obtained is entirely soluble in water, the whole is diluted with ice water and the sodium salt of benzanthrone-sulfonic acid is isolated by addition of sodium chloride. Instead of the benzanthrone-sulfonic acid the sulfonic acid of napthanthraquinone prepared in an analogous manner may be used.

We claim:

1. Light sensitive material which consists of a sheet support carrying a colored layer which layer changes their shade on exposure to light wherein the said layer comprises a dyestufi which is unstable to light and as a sensitizer a substance selected from the group consisting of anthraquinone and benzanthrone compounds.

2. Light sensitive material as claimed in claim 1 wherein the said dyestufi is water soluble.

3. Light sensitive material asclaimed in claim 6 basic group.

6. Light sensitive material which consists of a sheet support carrying a layer which comprises a dyestufl capable of bleaching out on exposure of the layer to light and as a sensitizer a substance selected from the group consisting of water soluble anthraquinone and benzanthrone compounds.

7. Light sensitive material as claimed in claim 6 wherein the said dyestuif is a water soluble dyestufl.

8. Light sensitive material as claimed in claim 6 wherein the said dyestuff is an azo dyestufl.

9. Lightsensitive material as claimed in claim 6 wherein the said dyestufi is a mono-azo dye stufl.

10. Light sensitive layer as claimed in claim 6 wherein the said dyestufl is a mono-azo dyestufl containing a basic group.

11. Light sensitive material which consists of a sheet support carrying a layer which com-' prises a dyestufl capable of bleaching out on exposure of the layer to light and as a sensitizer a substance selected from the group consisting 11 wherein the said dyestufl is a mono-azo dyestufl containing a basic group.

16. Light sensitive material which consists of a sheet support carrying a layer which comprises a dyestufi capable of bleaching out on exposure of the layer to light and as a sensitizer a substance selected from the group consisting of water soluble substantially colorless anthraquinone and benzanthrone compounds.

17. Light sensitive material according to claim 16 wherein the said dyestufl is a water soluble dyestufi'. 1 I

18. Light sensitive material as claimed in claim 16 wherein the said dyestufl is an azo dyestufi.

19. Light sensitive material as claimed in claim 16 wherein the said dyestuif is a mono-azo dyestun.-

20. Light sensitive layer as claimed in claim 16 wherein the said dyestufl is a mono-azo dyestufl containing a basic group.

21. Light sensitivematerial which consists of a sheet support carrying a layer which comprises an azo dyestui! capable of bleaching out on exposure of the layer to light and as a sensitizer a water soluble substantially colorless anthraquinone derivativewhich contains a sulfo group as a substituent in an aromatic nucleus.

22. Light sensitive material which consists of a cellulose hydrate foil which is impregnated with a mixture comprising a mono-azo dyestuif capable of bleaching out on exposure of the layer to light and a 'water soluble substantially colorless anthraquinone derivative which contains a sulfo group as a substituent in an aromatic nucleus.

23. Light sensitive material which consists of a cellulosehydrate foil which is impregnated with a mixture comprising a mono-azo dyestufi capable of bleaching out on exposure of the layer to light and 2.7-anthraquinone disulfonic acid.

24. Light sensitive material which consists of 

